Influence of phosphate status on phosphate uptake kinetics of maize (Zea mays) and soybean (Glycine max)

• Published in: Plant and soil 1990-06, Vol.124 (2), p.175-182
• Main Authors: Jungk, A. (Georg-August Univ., Goettingen (Germany). Inst. of Agricultural Chemistry), Asher, C.J, Edwards, D.G, Meyer, D
• Format: Article
• Language: English
• Subjects: ABSORCION DE SUBSTANCIAS NUTRITIVAS; ABSORPTION DE SUBSTANCES NUTRITIVES; Absorption. Translocation of ions and substances. Permeability; Agronomy. Soil science and plant productions; Biological and medical sciences; Corn; Crop harvesting; Economic plant physiology; FOSFATOS; Fundamental and applied biological sciences. Psychology; GLYCINE MAX; Kinetics; Nutrient solutions; NUTRIENT UPTAKE; Nutrition. Photosynthesis. Respiration. Metabolism; PHOSPHATE; PHOSPHATES; Plant nutrition; Plant physiology and development; Plant roots; Plants; Pretreatment; Soybeans; Water and solutes. Absorption, translocation and permeability; ZEA MAYS
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF00009256

To obtain plants of different P status, maize and soybean seedlings were grown for several weeks in flowing nutrient solution culture with P concentrations ranging from 0.03-100 µmol P L⁻¹ kept constant within treatments. P uptake kinetics of the roots were then determined with intact plants in short-term experiments by monitoring P depletion of a 3.5 L volume of nutrient solution in contact with the roots. Results show maximum influx, Imax, 5-fold higher in plants which had been raised in solution of low compared with high P concentration. Because P concentrations in the plants were increased with increase in external P concentration, Imax was negatively related to % P in shoots. Michaelis constants, Km, were also increased with increased pretreatment P concentration, only slightly with soybean, but by a factor of 3 with maize. The minimum P concentration, Cmin, where net influx equals zero, was found between 0.06 and 0.3 µmol L⁻¹ with a tendency to increase with pretreatment P concentration. Filtration of solutions at the end of the depletion experiment showed that part of the external P was associated with solid particles. It was concluded that plants markedly adapt P uptake kinetics to their P status, essentially by the increase of Imax, when internal P concentration decreases. Changes of Km and Cmin were of minor importance.